Patent GB-669385-A (GB)
Title: Improvements in multicavity magnetron devices
IPC: H01J25/587
Filed: 1946-12-23
Abstract: 669,385. Magnetrons. WESTERN ELECTRIC CO., Inc. Dec. 23, 1946 [April 5, 1944], No. 37774/46. Class 39 (i). A multicavity magnetron including a conductive block 13, Fig. 2, having a bore containing an anode member 17, and a cathode 30, has an output assembly supporting an output conductor 46 and including a coupler member 40 provided with a sleeve portion 42 fitting in and extending through an aperture 16 leading from a face of the block 13 to the bore, the anode member 17 abutting against the inner end of the sleeve 42, Fig. 7, whereby a coupling loop 47 carried by the output conductor 46 is disposed adjacent to the anode member 17. The anode member 17 comprises a plurality of resonent cavities 18 separated by anode segments 19 and is provided on its faces with recesses in which arcuate straps 20 are positioned. The bore is closed at each end by a plate 21 having an insert 22 therein of magnetic material which reduce the reluctance of the flux path for the magnetic field. Overheating of the anode assembly during operation is prevented by cooling fins 65, Fig. 1, having edge portions fitted in slots in the block 13 and provided with curved portions 68 allowing passage of a tool for adjusting the tuner screw 57 referred to later. Two further apertures 15, Fig. 3, extend from another face of the block 13 to the bore, a second coupler member 23 associated with means carrying two leading-in conductors 28 being seated on said face, the cathode 30 being supported between the leading-in conductors 28 or between metallic supports 29 joined to the leading-in conductors. The stem 26, carrying the leading-in conductors 28, is enclosed 'by a protective cap 69 of vitreous material. An insulating stem portion 44, 45 is sealed to the output conductor 46 and to the coupler member 40 on which is mounted a tubular conductor 48 intersected by a rectangular waveguide element 49 provided with a coupling flange 50, the output conductor 46 and the tubular conductor 48 forming a coaxial line. The wave-guide element 49 is provided with a deformable diaphragm member 60, Fig. 5, for matching the impedance thereof and that of the coaxial line 46, 48. A tuning assembly for'the magnetron extends through apertures in the block 13 and anode 17 to project into one of the anode cavities 18 and comprises a flexible diaphragm 54 carrying a plug member 53 on one side and a screw 57 on the other side co-operating with a rotatable threaded sleeve 56 mounted on the block 13. The bearing surfaces of the tuning structure are of stainless steel to leaded bronze in order to prevent seizing due to high temperatures during fabrication. The cathode assembly, Fig. 6, comprises a nickel cylinder 31 provided with circular flanges 33 on one of which is an integral rib 34. A mesh cylinder 35 having an electron emissive coating surrounds the cylinder 31. One flange 33 is provided with a recess containing a cylindrical insert 36 of insulating material carrying a metallic eyelet 37,. a helical, heater element 39 coated with insulating material being welded at one end to the eyelet 37 and at the other end to the rib 34.